1. Field of the Invention
This invention relates to fault tolerant signaling and, in its presently preferred application, to fault tolerant resetting within an ACD.
2. Description of the Related Art
As is well known in the art, an automatic call distributor (ACD) is commonly used to aid a business or the like that must answer a heavy volume of incoming telephone calls. An ACD, usually on the business premises, answers the inbound calls and accomplishes one or more of the following: routes and prioritizes incoming calls; causes callers to wait till answered; provides management with data; aids in automating call answering and/or recording.
An ACD is often very sophisticated and complex in nature and thus is subject to failures in hardware and/or software. Since reducing ACD malfunctions and/or down-time is important to the ACD user, an ACD often includes a capability of reporting status, faults, etc. to a remote maintenance station where an operator/monitor can interpret the reports and send appropriate instructions/signals back to the ACD so that it will effect certain corrections and/or cures. For example, an ACD element X might report to the maintenance operator a problem with ACD element Y, whereupon the operator signals/instructs X to effect or command corrective action for Y.
Additionally, the ACD is often sophisticated and powerful enough to contain self-monitoring and self-correction schemes. That is, an ACD element X might monitor some parameter of ACD element Y, and if X is not satisfied with Y, X could provide Y a command/signal to effect corrective or curative action.
In some instances, however, a particular corrective or curative action can itself create sufficient annoyance in processing that it is desirable to have a high degree of confidence, that the action is really needed, before the corrective action is taken.
For example, since a fault in element X might erroneously command corrective action for element Y, X is often not designed or permitted to effect certain corrective actions for Y which the user finds overly annoying and/or disruptive. Instead, in order to achieve the level of confidence desired, manual intervention is often involved. That is, a maintenance person comes to the ACD site and tests and determines whether or not Y actually needs assistance.
In accordance with the present invention, there is featured the provision of method and apparatus whereby a signaled device reacts to "authorized" signals or messages but ignores spurious, unauthorized, erroneous, or unintentional messages/signals. A fault-tolerant quality is provided, namely: a device continues to operate properly despite some fault that evokes an unauthorized message to do otherwise. In the context of ACDs, self-curing and/or remote-curing may be achieved with the desired confidence level, thereby obviating the use of manual intervention. In the preferred application, there is employed a concurrency scheme whereby two autonomous entities must agree upon a reset action, that is desired by one of the two entities, before that action is effected by a reset targeted entity. The invention prevents resets from being falsely triggered by a single-point failure, or by the insertion or removal of any single card.